UPDATE:Crist shrugged off the poll results this morning, telling reporters that his main responsibility was to govern and “fight for the people.” Rubio’s campaign sent out a press release announcing the results, but did not offer a reaction.

Marco Rubio, who once trailed Gov. Charlie Crist by 31 points in polling on the 2010 Republican Senate primary, now has a narrow lead in the race, according to a Quinnipiac University poll released this morning.

The poll shows former Florida House speaker Rubio with 47 percent to Crist’s 44 percent among Republicans, a lead within the poll’s margin of error.

The poll also finds Florida voters disapprove of President Obama’s job performance by a 49-to-45 percent margin.

In Obama’s latest numbers, 51 percent of the state’s independent voters disapprove of his job performance and 44 percent approve.

Rubio’s lead over Crist, while narrow, is “not a fluke,” says Quinnipiac’s Peter Brown. When Republican voters were asked who is more “consistently conservative,” they picked Rubio by a 48-to-34 percent margin. Rubio also leads 45-40 when Republicans were asked which candidate “shares your values.”

Brown marveled at Rubio’s surge over the past seven months.

“Who would have thunk it? A former state lawmaker virtually unknown outside of his South Florida home whose challenge to an exceedingly popular sitting governor for a U.S. Senate nomination had many insiders scratching their heads. He enters the race 31 points behind and seven months later sneaks into the lead,” said Brown, who is assistant director of Quinnipiac’s Polling Institute.

The statewide poll of 1,618 voters has a 2.4 percent margin of error. The Republican sample of 678 voters has a 3.8 percent margin of error.

Crist had a 54-to-23 percent lead over Rubio in a Quinnipiac poll last June. Crist led by 29 points in August and 15 points in Quinnipiac’s last Florida Senate poll in October.